Method of assembling and mounting an aperture mask in a mask-panel assembly of a cathode-ray tube using a full surface spacer

ABSTRACT

The method includes supporting a panel of a cathode-ray tube in a given position, placing on the inner surface of the faceplate a flexible spacer having a predetermined thickness related to the desired spacing q between an aperture mask to be assembled with the panel and the faceplate, and then, placing the mask against the flexible spacer. The spacer is forced against the inner surface of the faceplate and the mask is forced against the spacer. The mask, frame and frame supports are assembled and detachably mounted on the studs of the panel. In a particular form of the method, the mask is detachably mounted in the panel by welding the support members to the frame and by welding the mask to the frame while maintaining the mask conformed to the desired contour at the desired spacing q.

United States Patent [5 METHOD OF ASSEMBLINGAND 1 MOUNTING AN APERTURE MASK IN Primary Examiner-Robert D. Baldwin MASK.PANEL ASSEMBLY OF A Assistant Examiner-Richard Bernard Lazarus CATHODE-RAY TUBE USING A. FULL Alma-Glen" Bruesfle SURFACE SPACER [57] ABSTRACT 1 l [72] Inventor f Jr The method includes supporting a panel of a cathoderay tube in a given position, placing on the inner sur- Assigneer RCA collmlatlon face of the faceplate a flexible spacer having a predetermined thickness related to the desired spacing [22] Ffled' March 1971 q between an aperture mask to be assembled with the 1 [21] Appl. N 121, panel and the faceplate, and then, placing the mask against the flexible spacer. The spacer is forced against the inner surface of the faceplate and the mask is forced against the spacer. The mask, frame and frame supports are assembled and detachably [58] new of Search 29/2115 mounted on the studs of the panel. In a particularform of the method, the mask is detachably mounted [56] References Cited in the panel by welding the support members to the UNITED STATES PATENTS frarne and by welding the mask to the frame while 3 335 479 8/1967 Morten 29/25 15 X maintaining the mask conformed to the desiredcon- 3,482,286 12/1969 Fassettet a1.. ...'..29/25.l1 X

tour at the desired spacing q;

8 Claims, 2 Drawing Figures PATENTED 0m 3 1 m2 IIQVENTOR. Frank R. Ragland,Jr BY ATTORNEY APERTURE MASK IN A MASK-PANEL ASSEMBLY OF A CATHODE-RAY TUBE'USING A FULL SURFACE SPACER BACKGROUND OF THE INVENTION The invention relates to a method of assembling and mounting an aperture mask in the mask-panel assembly of a cathode-ray tube with the aperture mask in a particular spaced relationship in the faceplate panel of thecathode-ray tube, and particularly a color-television picture tube.

Commercial shadow-mask-type picture tubes for color-television receivers include a faceplate having, on its inner surface, a mosaic viewing screen of differently emissive phosphor dots, and an electron-gun structure for projecting plural electron beams towards the screen. A domed aperture or shadow mask is'attached to a frame and nested in the faceplate panel with a prescribed spacing between the mask and the screen from center to edge, for example, as described in U. S. Pat. No. 3,109,116 to D. W. Epstein et al. The prescribed spacing is designated q and is defined to be the distance between the viewing window and the mask measured perpendicularly to the faceplate. In the operation of the tube, the electron beams pass through apertures in-the mask to selectively excite the phosphor dots.

- In one commercial method for assembling a rectangularly shaped panel, shadow mask, and frame assembly with a prescribed q, a plurality of spacers is positioned between the mask and the panel near the corners and at the center of the panel to contact the inner contour of the panel with one end of the spacer, and a frame with a. mask loosely fitted thereon is located in the panel on frame-positioning means with the mask in plural contact with the other end of the spacers. Pressure is applied to seat the mask against the spacers so to conform the mask contour more closely to that of the panel. Then, with the pressure still applied, the mask is attached to the frame at a plurality of separated perimetric areas. Then, the pressure is removed, and the spacers'are removed. A disadvantage of this method is that the spacers are positioned at discrete locations, thereby establishing a spacing q only at these discrete locations. Variations in the formed mask contour or in the faceplate contour at the discrete locations of the spacers may result in the establishment of an unsatisfactory final spacing q between the faceplate and the mask and subsequently an unsatisfactory viewed image from an assembled tube.

In another prior method for' assembling a panel, shadow mask and frame assembly with a prescribed q, described, for example, in U. S. Pat. No. 3,482,286 to G. F. Fassett et al, a q-spacing gauge member having multiple variable distance-measuring units is positioned on the inner concave surface'of the faceplate. A preassembled mask-frame assembly is inserted within the panel over the gauge member and temporarily mounted on the panel studs by means of leaf springs frictionally engaging hook plates attached to the frame. The mask is moved to the desired position, and the qdistances are measured at discrete locations. After the desired q distances are obtained, the leaf springs are welded to the hook plates on the frame and the inserted gauge is removed.

panel comprising a 2 This assembly method establishes the spacing q by measurement at discrete locations, resulting in the same disadvantages as described in the previous method In addition, in this method, the mask and frame are preassembled prior to establishment of the spacing q at the discrete locations. Therefore, additional variations in the spacing q can occur since the preassembled mask and frame form a semirigid assembly, which may result in additional mask contour variation. A spacing q which is different from the desired spacing q may result in a nonuniform viewed image in the assembled tube.

SUMMARY OF THE INVENTION The novel method includes supporting a panel in a given position, placing on the inner surface of the faceplate a flexible spacer having a predetermined thickness related to the prescribed spacing q between a mask to be assembled with the panel and the faceplate, and then, placing a mask in contact with the flexible spacer. Then, the spacer is forced into substantially full surface contact against the inner surface of the faceplate, the mask surface is forced into substantially continuous contact with the spacer surface and the mask, frame, and frame supports are assembled and detachably mounted on the studs of said panel.

Unlike the prior methods, by forcing the faceplate surface, the spacer, and the mask surface into substantially continuous contact, the novel method spaces the mask and the faceplate surface over the entire surface of the mask in a prescribed manner. This eliminates improper q spacings which may result from mask or faceplate contour variations over one or more discrete spacing locations.

A more specific form of the novel method includes a full surface conformation of the contour of the mask to the contour of the panel at the desired q spacing prior to the attachment of the mask to the frame. This eliminates variations in the mask contour which may occur from the attachment of the mask to the frame prior to conforming'the mask contour to the contour of the faceplate. Furthermore, the novel process also permits the attachment of the mask to the frame and the attachment of the frame support members to the frame in the same assembly station, thereby eliminating the need for preassembly of either the frame and the support members or the frame and the mask. This provides a further economy in assembling and mounting Y the mask in the panel.

' BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERRED EMBODIMENT FIGS. 1 and 2 illustrate an apparatus 10 for positioning a mask in the panel assembly 11 of a shadow-masktype color-television picture tube. The panel assembly 11 includes a panel 12 and a mask-frame assembly 13. The panel 12 includesa faceplate 14 and sidewalls 15 having four studs 16 extending inwardly therefrom. The mask-frame assembly 13 includes a multiapertured mask 17 having a perimetric skirt 18 and an apertured portion 19, a frame assembly 20, including a frame 21 having a vertically upstanding flange 22 parallel to the skirt 18 and four hook plates 23 attached to the frame 21. Frame-support members comprising four leaf springs 24 are each attached at one end to one of the hook plates 23, and each has a hole 25 at the'other end to detachably engage one of the four studs 16.

In this example, the apparatus 10 for practicing the invention comprises a flexible spacer 26 having substantially the same shape as the inside surface of the faceplate 14 and a flexible sheet member 27 having substantially the same shape as the apertured portion 19 of themask 17. The spacer 26 has a predetermined thickness related to the prescribed spacing q between the assembled'mask 17 and the inside surface of the faceplate 14. It is preferred that the spacer 26 be constructed from rubber or other suitable flexible material.

The spacer 26 has a first set of spaced interconnect-' ing channels 28 on one side which contacts the surface of the faceplate l4 and a substantially smooth surface on the other side which contacts the surface of the mask 17. v

The first set of channels 28 includes a first set of parallel longitudinal channels 29 and a first connecting cross channel 30. The first set of channels 28 extends over a portion of the surface area of the spacer 26 substantially the size of the faceplate 14 without the ends of the channels extending past the edge of the spacer 26. Since the first set of channels 28 contacts the faceplate 14, which is a rigid member, the number of channels and the width of the channels need only be sufficient to provide clamping contact of the spacer 26 with the faceplate 14 as will be described later.

The flexible sheet member 27 has a second set of spaced interconnecting channels 31 on one side which contacts the other surface of the mask 17.

The second set of channels 31 also includes a second set of parallel longitudinal channels 32 and a second connecting cross channel 33. The second set of channels 31 extends approximately over the surface of the flexible sheet member 27, which is the same size as the inside surface of the mask 17. It is preferred that the number of the second set of channels 31 and the width of the second set of channels 31 be determined by the material of the mask and the thickness of the mask. For example, for a color-television picture tube 'with a mild steel mask approximately 0.006-inch thick, it is preferred that the width of each of the channels is approximately one-sixteenth inch and the spacing between channels is approximately one-eighth inch.

When the spacer 26 is positioned in contact with the I surface of the faceplate 14, the open sides of the first set of channels 28 are closed by the surface of the faceplate 14, thereby forming a first chamber v34 between the spacer 26 and the surface of the faceplate 14.

When the mask 17 ispositioned in contact with the other side of the spacer 2 6, the second set of channels 31 is over a portion of the apertured portion 19 of the mask 17. When theflexible sheet member 27 is positioned over the mask 17, the open sides of the second set of channels 31 are closed by the mask 17 thereby forming a second chamber 35 between the spacer 26 and the flexible sheet member 27. The second chamber 35 includes the apertures in the mask 17 which are within the second set of channels 31.

- A vacuum source 36 isconnected through a control valve 37 to the second chamber 35 by a vacuum hose 38, and the second chamber 35 is connected to the first chamber 34 by an opening 39 through the spacer 26 between the first cross channel 30 and the second cross channel 33. In the preferred embodiment the vacuum hose 38 connects through the flexible sheet member 27 approximately at the center of the panel 12. The apparatus 10 also includes welding means (not shown) for attaching the skirt 18 of the mask 17 to the vertical flange 22 of the frame 21 and for attaching the four leaf springs 24 to the four hook plates 23 comprising a portable or hand carried welding unit which is well known.

In the operation of the apparatus 10, a panel 12 with faceplate 14 is supported in a fixture (not shown) with the inner surface of the faceplate 14 facing upwardly. The flexible spacer 26 is positioned on the inner surface of the faceplate 14. The extent to which the spacer 26 conforms to the contour of the inner surface of the faceplate 14 is determined by the extremity of the contour variations in the Faceplate l4 and the flexibility of the spacer 26. The spacer 26, resting on the faceplate 14 by its own weight, substantially conforms to the general contour of the faceplate 14.

A mask 17 is then placed on the spacer 26, also resting against the spacer 26 by its own weight. The extent which the mask 26 conforms to the contour of the spacer 26 is determined by the extremity of contour variations in the mask 17 and in the faceplate 14.

Then, the entire surface of the spacer 26 is forced into substantially full surface contact with the surface of the faceplate 14, and the entire surface of the mask 17 is forced into substantially full surface contact with the spacer 26 by applying a vacuum to the interconnected first and second chambers 34 and 35 respectively. The vacuum in the first set of channels 28 forces the spacer 26 against the inner surface of the faceplate 14, and the vacuum in the second set of channels 31, which include the apertures within the second set of channels 31, forces the flexible sheet member 27 towards the spacer 26 thereby forcing the mask 17 against the spacer 26. The vacuum is applied through the vacuum hose 38 by opening the control valve 37 connecting to the vacuum source .36.

A suitable vacuum is approximately 10 to 14 poundsper-square-inch vacuum. When the first and second chambers 34 and 35 respectively are under a vacuum,

atmospheric pressure applies force equal to that I created by the vacuum against the walls of the chamber. This force directed against the closed sides of the first and second set of channels 28 and 31 respecplates 23 is positioned in the panel 12 oriented with the skirt 18 of the mask 17 overlappingthevertical flange 22 on the frame 21. Fourleaf springs 24 are placed in the panel 12 by engagingeach of the holes 25 in one end with each of the four studs 16 and frictionally engaging the other end with each of the four hook plates four hook plates 23 and four leaf springs 24, preassembled using the particular panel 12 as a fixture in a well known manner, is placed in the particular panel 12 and attachably supported in the panel 12 with the four leaf springs 24 engaging the four studs 16. The mask 17 is then attached to the frame 21 by welding the skirt 18 to the vertical flange 22.

After the mask 17 is detachably mounted in the panel, the vacuum is released by operating the control valve 37 to close the first and second chambers 34 and 35 respectively to the vacuum source 36 and to open the vacuum hose 38 to atmospheric pressure. The mask-frame assembly 13, the flexible sheet member 27 and the spacer 26 are removed from the panel 12, and the mask-frame assembly 13 is remounted in the panel 12 for further processing.

Although it is described that the mask 17 is forced against the spacer 26 and the spacer against the faceplate 14 to conform the contour of the mask 17 to the contour of the inner surface of the faceplate 14 at the desired spacing q established from the spacer thickness by applying a vacuum to channels formed in a surface of the spacer 26 and a surface of the flexible sheet member 27, other methods can be used to force the mask 17 to conform to the contour of the spacer 26 and the spacer 26 to conform to the contour of the surface of the faceplate 14. For example, with a relatively thin mask, the flexible sheet member 27 may be sufficiently thick, for example, approximately l-inch thick, and resilient and include a rigid backing member. The force would then be applied by hand or mechanical means, rather than by atmospheric pressure, by pushmember 27 are described, it is only necessary to have connected indentations in the surface of the sheet I member 27 in contact with the mask 17 which when I closed by the surface of the mask 17 form a vacuum chamber. For example, a rubber-coated section of open wire mesh can be positioned against the mask surface between the mask and a smooth surface sheet member. The voids in the wire mesh would then form the vacuum chamber, and the crossover of the mesh wires would then form connecting channels. In addition, the second set of connecting channels 31 could be formed in the side of the spacer 26 in contact with the mask 17 andthe sheet member 27 with a smooth surface in contact with the mask 17.

lclaimz 1. In. themanufacture of a cathode-ray tube maskpanel assembly including a panel having a contoured faceplate and sidewalls, at least three support studs extending from said sidewall, a frame assembly including a frame and frame support members, and an aperture mask having an apertured portion attached to the frame, the method of mounting and assembling the mask in said panel comprising the steps of a. supporting a panel in a given position,

b. placingon the inner surface of said faceplate panel -a flexible spacer having a predetermined thickness related to a prescribed spacing between said mask to be assembled and said faceplate, said spacer having surface dimensions at least the same size as that of the apertured portion of said mask,

c. then, placing said mask loosely in surface contact against said spacer,

d. forcing substantially the entire surface of said spacer into substantial contact against said contoured faceplate,

e. forcing substantially the entire surface of said mask into substantial contact with said spacer, and

f. then, detachably mounting and permanently assembling said mask, said frame and said frame supports on said studs of said panel while continuing said forcing steps (d) and (e).

2. The method of claim 1 including the additional steps of g. discontinuing said forcing steps (d) and (e),

h. removing said. mask and said spacer from said panel, and

i. remounting said mask in said panel in said mounted position. i

3. The method of claim 2 wherein said support members include at least three hook plates preassembled with said frame and a corresponding number of leaf springs each having a hole in one end, the steps between step (b) and step (c) comprising j. placing a frame preassembled with at least three hook plates in said panel oriented with said masks, and

k. placing one leaf spring corresponding to each of said hook plates on said panel by engaging the hole in one end with a stud and frictionally engaging the other end with said hook plate to detachably mount said mask on said panel.

4. The method of claim 3 wherein said mounting step comprises i. welding each of said leaf springs to said corresponding hook plate to detachably mount said frame in said panel, and

ii. welding said mask to said frame to detachably mount said mask in said panel.

5. The method of claim 3 wherein said frame is preassembled with said support members, said mounting step comprising welding said mask to said frame to detachably mount said mask in said panel.

6. The method of claim 1 wherein said flexible spacer has a first set of connecting channels in the surface in contact with the inside surface of said faceplate, including prior to step (f) and additional steps of i. placing a flexible sheet member having a second set of connecting channels loosely on said mask with said second set of channels incontact withsaid mask, said sheet member the same size as said with said spacer. I I 7. The method of claim 6 wherein said frame is preassembled with said support members, said mounting step comprises welding said mask to said frame.

8; The method of claim 6 wherein said first set of connected channels is equally spaced over said faceplate surface and said second set of connecting channels is equally spaced over said apertured surface of said mask when said spacer is positioned between said mask and said faceplate and said flexible sheet member is positioned against said mask. 

1. In the manufacture of a cathode-ray tube mask-panel assembly including a panel having a contoured faceplate and sidewalls, at least three support studs extending from said sidewall, a frame assembly including a frame and frame support members, and an aperture mask having an apertured portion attached to the frame, the method of mounting and assembling the mask in said panel comprising the steps of a. supporting a panel in a given position, b. placing on the inner surface of said faceplate panel a flexible spacer having a predetermined thickness related to a prescribed spacing between said mask to be assembled and said faceplate, said spacer having surface dimensions at least the same size as that of the apertured portion of said mask, c. then, placing said mask loosely in surface contact against said spacer, d. forcing substantially the entire surface of said spacer into substantial contact against said contoured faceplate, e. forcing substantially the entire surface of said mask into substantial contact with said spacer, and f. then, detachably mounting and permanently assembling said mask, said frame and said frame supports on said studs of said panel while continuing said forcing steps (d) and (e).
 2. The method of claim 1 including the additional steps of g. discontinuing said forcing steps (d) and (e), h. removing said mask and said spacer from said panel, and i. remounting said mask in said panel in said mounted position.
 3. The method of claim 2 wherein said support members include at least three hook plates preassembled with said frame and a corresponding number of leaf springs each having a hole in one end, the steps between step (b) and step (c) comprising j. placing a frame preassembled with at least three hook plates in said panel oriented with said masks, and k. placing one leaf spring corresponding to each of said hook plates on said panel by engaging the hole in one end with a stud and frictionally engaging the other end with said hook plate to detachably moUnt said mask on said panel.
 4. The method of claim 3 wherein said mounting step comprises i. welding each of said leaf springs to said corresponding hook plate to detachably mount said frame in said panel, and ii. welding said mask to said frame to detachably mount said mask in said panel.
 5. The method of claim 3 wherein said frame is preassembled with said support members, said mounting step comprising welding said mask to said frame to detachably mount said mask in said panel.
 6. The method of claim 1 wherein said flexible spacer has a first set of connecting channels in the surface in contact with the inside surface of said faceplate, including prior to step (f) and additional steps of i. placing a flexible sheet member having a second set of connecting channels loosely on said mask with said second set of channels in contact with said mask, said sheet member the same size as said apertured portion of said mask, ii. applying a vacuum to a first set of connecting channels on said spacer to force said spacer into substantially full surface contact with said inner surface of said faceplate, and iii. applying a vacuum to a second set of connecting channels in said flexible sheet member to force said mask into substantially full surface contact with said spacer.
 7. The method of claim 6 wherein said frame is preassembled with said support members, said mounting step comprises welding said mask to said frame.
 8. The method of claim 6 wherein said first set of connected channels is equally spaced over said faceplate surface and said second set of connecting channels is equally spaced over said apertured surface of said mask when said spacer is positioned between said mask and said faceplate and said flexible sheet member is positioned against said mask. 